stove pipe and stove top temps

[Dmriggs]

I've read several places where the internal pipe temp is about twice what you see on a magnetic thermometer. Is this the case with stove top temps as well?
I've read some posts where the pipe temp is maintaining at 500 to 600. Would that be what they are reading on the thermometer or multiplying the reading by 2?
I've read where creosote can ignite at about 600 and I realize we do our best to eliminate the danger but, how much build up would there be, for it to possibly ignite?
I know a few guys who run with no thermometer at all! I think that would worry me to not actually have some idea what is going on inside temp wise.

 

[pen]

I've read several places where the internal pipe temp is about twice what you see on a magnetic thermometer. Is this the case with stove top temps as well?
I've read some posts where the pipe temp is maintaining at 500 to 600. Would that be what they are reading on the thermometer or multiplying the reading by 2?
I've read where creosote can ignite at about 600 and I realize we do our best to eliminate the danger but, how much build up would there be, for it to possibly ignite?
I know a few guys who run with no thermometer at all! I think that would worry me to not actually have some idea what is going on inside temp wise.

These numbers can vary by stove, chimney type and length, even type/brand of thermometer, lots of variables. In general, burn using the best fuel you have, keep things from smoldering, and watch the chimney accumulation as compared to what you are seeing on your thermometers and tune things from there.

I wish I could give you some hard and fast guidelines, but in general some of this really is a blend of art and science.

 

[Dmriggs]

T

These numbers can vary by stove, chimney type and length, even type/brand of thermometer, lots of variables. In general, burn using the best fuel you have, keep things from smoldering, and watch the chimney accumulation as compared to what you are seeing on your thermometers and tune things from there.

I wish I could give you some hard and fast guidelines, but in general some of this really is a blend of art and science.

Thanks,
Unfortunately I have to be gone for 13 hours a day and, I have to keep things sealed to have any type of live coals when I get home. I'm learning to run it hotter when I get home to lessen the build up in the stove pipe and monitor the chimney once a week to see how things are fairing. I have two runs of 24 inch single wall pipe, one elevated at about 20 degrees coming from the stove and one vertical into and elbowed into the thimble. Upon taking it apart to analyze buildup, the section nearest the stove looked fair but, the vertical section looked glazed somewhat. I don't I was running it hot enough plus, I don't think the joints were maybe as tight a fit as needed. I cleaned all pipe, refitted, applied screws to the joints and sealed them with furnace cement. I'll check it again in a week or so. Also have been tapping on the pipe to make sure I'm getting the metallic sound compared to a thud. Seems to be helping with a small hotter fire.

 

[chemical_man]

Unfortunately I have to be gone for 13 hours a day and

I am pretty much in the same boat as you, empty house for a while and you do have to sleep at night. You just have to learn your stove's behavior and how it burns. How dry is your wood (when did you buy it? Stacked it where? type?)? Where it is now stored (and how if outside)?

If you haven't seen my thread: https://www.hearth.com/talk/threads/stove-loading-pics.151473/#post-2033332

I've started filling mine more, it burns hotter and longer and I haven't burned the house down. Something to consider.

As for creosote igniting, it happens. My first year was very crappy and the winter was horrible. More rain than usual followed by flash freezes combined with an inferior outside wood stack cover led to wet wood (also noted my preferred location for wood (next to house door) was not a good spot for drying in the summer). So, this led to cooler gases and creosote and one day on a hot burn it ignited. Fortunately I caught it quickly and was somehow able to control it myself and was happy I had paid extra for the piping.
Since then, I sweep after 4-6 weeks of burning. I've learned to gauge the stovetop temps by feel and confirmed with IR gun (this way I can quickly determine if I am running well plus the kids usually have the gun somewhere else). I keep meaning to get a probe thermometer, one of these days....

 

[Highbeam]

I've read several places where the internal pipe temp is about twice what you see on a magnetic thermometer. Is this the case with stove top temps as well?
I've read some posts where the pipe temp is maintaining at 500 to 600. Would that be what they are reading on the thermometer or multiplying the reading by 2?
I've read where creosote can ignite at about 600 and I realize we do our best to eliminate the danger but, how much build up would there be, for it to possibly ignite?
I know a few guys who run with no thermometer at all! I think that would worry me to not actually have some idea what is going on inside temp wise.

You have to be careful with your listening. Many folks blurt out a "flue temp" without being specific about whether that is surface temp, surface temp*2, or internal flue temp measured with a real probe meter. If somebody calls out a stove top temp you can be certain that it is the surface temp at the hottest part they could measure.

This business about creosote igniting at 600 is an example of the incomplete information. That must be a surface temp of the flue but you can't be sure. With my non-cat hearthstone I ran internal flue temps past 1000 with every load, sometimes to an indicated 1250 on the probe meter. Never had a chimney fire. Since you don't know what that 600 temp is supposed to be you need to throw out that claim.

 

[Woody Stover]

You can put your stove in your signature so folks have a better idea about the variables involved. With a cat stove you can cut the air pretty low, and it will still burn clean all day. If you have a non-cat and are cutting the air too far to try to stretch the burn, you may kill the secondary burn which will produce much more build-up in the flue. If you are running an old smoke-bomber stove, you have to have internal stove temp around 1100 degrees to burn relatively clean, and with no secondary burn, your loads won't last very long at all. I think the stove-top meter will probably also read about 1/2 of the actual internal temp. Cat stoves have the lowest flue temps since they can run less air and still burn clean. You can experiment with your stove, then go outside and look at what's coming out of the stack to gauge how much creo buildup you might be promoting.

 

[begreen]

Pen is exactly right. There are a lot of installation variables that can effect the temp. Surface stove pipe temps may vary quite a bit depending on the placement of the thermometer and the swirl of flue gases in the pipe. As the flue gases slow down the surface can read hotter. For example, a flue pipe will probably read hotter if there is an elbow a few feet above the thermometer than if the pipe goes straight up to the chimney. Probe temps are more accurate and do not need a multiplier.

 

[BradleyW]

My somewhat educated guess is that every system has some kind of equilibrium that works for that system. You need to balance everything (stove top temp, flue temp, how open your air is, etc.) in order to best achieve your goals, which are probably the most efficient burn possible, with minimum chance of creosote formation. Your numbers probably won't be perfect, unless you have the perfect system, which I certainly do not. I have two ninety degree turns in my stove pipe (it was like that when I bought the house). The chimney is a little short. So basically, I think I suffer a little on the efficiency side of things in order not to have smoke coming out of my chimney and creosote forming. But even though it isn't perfect, it still works for me.

 

[Squisher]

Is it fine to run a probe on single wall pipe?

 

[Round Stove Guy]

My dad had a magnetic spring temp gauge stuck on his stove pipe, the stove was very hot and the gauge was reading 0 degrees F. I got rid of it.
In my stove and in my dad's stove I use a barbecue grill lid temp gauge, but some don't go very high. I also use a probe temp gauge to verify the barbecue gauges are accurate, some can be off by 100 degrees F or more. Average cost for a barbecue grill gauge is $20.

 

[pen]

Is it fine to run a probe on single wall pipe?

You can, but the burn zone recommendations printed on it will not be correct. I've tested a probe on single wall just for fun, and the proper condar magnetic reads just as quickly to changing temps as the probe does.

On single wall, the magnetic is the way to go as a mechanical probe provides no advantage.

 

[bioman]

I know that at 900* my magnetic thermo started sliding down the pipe & it will do it every time on single wall pipe. I use probes on my double wall pipe in the house & a cat probe also. I just like to know whats really going on.

 

[Round Stove Guy]

I am sorry, there is no way a barbecue probe is slower or the same as a magnetic temp gauge. Convection... hot air (smoke) rising to fast will not contact (exchange heat) nearly as fast. Based on thermodynamics the temperature of the "fluid" will always be higher than the temperature of the outside surface of a "pipe". Plain and simple. Burn zone... look at the actual temperature and keep it above or below what your owners manual says.

 

[Squisher]

I know that at 900* my magnetic thermo started sliding down the pipe & it will do it every time on single wall pipe. I use probes on my double wall pipe in the house & a cat probe also. I just like to know whats really going on.

Isn't 900 on a magnetic thermometer dipping into the dangerous zone? And I'll assume that when you were hitting 900 with a magnet thermometer it wasn't on double wall pipe. I like to know what's going on too which is why I have stovetop and two stovepipe thermometers(magnetic condar and washer thermocouple auberins unit). I will say for me so far all of my thermometers seem to be quite accurate and never contradict each other.

 

[pen]

I am sorry, there is no way a barbecue probe is slower or the same as a magnetic temp gauge. Convection... hot air (smoke) rising to fast will not contact (exchange heat) nearly as fast. Based on thermodynamics the temperature of the "fluid" will always be higher than the temperature of the outside surface of a "pipe". Plain and simple. Burn zone... look at the actual temperature and keep it above or below what your owners manual says.

You are assuming the conduction of heat through the probe will be faster to make its bimetallic strip change than what a surface gauge can do.

I've used bbq gauges on bbq's and condar probes on stove pipes for years. Unless that bbq's probe goes to over 1k Fahrenheit, it's way too low for the actual temps in there.

A bunch of us did a lot of testing with probes, single wall pipe, etc, 5-6 years ago. Here's a link to see some of what we did back then https://www.hearth.com/talk/threads/3-39-condar-probe-vs-3-19-condar-probe-test-results.63980/

 

[Round Stove Guy]

I am going to go and read the link you provided but I am going to ask, at what temp does your surface gauge go up to? Also, if your chimney/flue temps are over 600 degrees F, you have a bad stove.

I am using and had experience only using on a single wall - black stove pipe.

 

[begreen]

My dad had a magnetic spring temp gauge stuck on his stove pipe, the stove was very hot and the gauge was reading 0 degrees F. I got rid of it.
In my stove and in my dad's stove I use a barbecue grill lid temp gauge, but some don't go very high. I also use a probe temp gauge to verify the barbecue gauges are accurate, some can be off by 100 degrees F or more. Average cost for a barbecue grill gauge is $20.

View attachment 172070 View attachment 172071

A flue thermometer should go up to at least 1000F.
That needle would get pegged daily on most stoves, particularly on startup. Our stove typically will go up to around 800F on launch with a full load of dry wood. Hit 1000F on the probe thermometer briefly this morning when I stepped away for just a minute.

 

[begreen]

Isn't 900 on a magnetic thermometer dipping into the dangerous zone? And I'll assume that when you were hitting 900 with a magnet thermometer it wasn't on double wall pipe. I like to know what's going on too which is why I have stovetop and two stovepipe thermometers(magnetic condar and washer thermocouple auberins unit). I will say for me so far all of my thermometers seem to be quite accurate and never contradict each other.

Yes, that is seriously hot. If surface temps are 900F then interior temp is >1300F . In the dark that pipe would be glowing.

 

[Round Stove Guy]

I read the older post. If you look at the pictures of where the temperature gauges were, a person can see a chance of error. When you measure the temperature of a "pipe" in the vertical orientation and then measure the temperature at an elbow and then the horizontal orientation.... Just imagine fluid dynamics, when going around a corner you want a transition to be as long as possible. If you make a sharp 90 degree angle, you cause a "bottle neck" and the fluids will "pause" and cause the most vertical part of the pipe to gather more heat.

I read a book on older boiler stoves that used 6 or 8 inch pipes to supply radiators. But, it was only 1 pipe to each radiator, the hot water flowed on the top of the pipe and the "colder" water would flow back to the boiler on the bottom of the same pipe.

 

[Squisher]

What book was that?

 

[Round Stove Guy]

It was 20 years ago and I am still looking for it. I found the book at Alexander Library but it was an inter-library loan. I looked online line and I know the book was old, I am still looking... I believe it is also called a gravity hot-water heating system.

 

[BrotherBart]

Just do a google search for single pipe radiators and you will find a ton of info.

 

[Squisher]

That is some crazy stuff. It never ceases to amaze me what people have managed to figure out and design.